The abnormal binding to albumin of tryptophan (and drugs) in chronic renal failure will be studied. By determining the correlation between the magnitude of abnormal binding and the degree and nature of renal disease it will be possible to narrow down the possible causes for this derangement and to determine whether the kidney is directly or only indirectly causative in its development. Finally, in normal subjects and patients with acute and chronic uremia direct biochemical approaches will be used to measure important properties of albumin - sulfhydryl content, the distribution of microforms, the nature of tightly bound ligands. The binding by micro-forms of albumin, isolated by standard fractionation as well as isoelectric focusing will be studied.